Is this right?
Is this right?
I have read all of the Herbie post and the first 44 pages of this one. I have noticed that everyone is asking the same questions and the BeanAnimal gets too many PMs. SO, I hope I am not stepping on toes, but have I got this right?
General Theory
There are two threads with similar designs the Herbie and the BeanAnimal this will hopefully explain the difference between the two and how they work.
The main theory behind this is a siphon drawing the water in. As long as the siphon does not create a vortex and suck air it is silent. The next step is that the output must be under water otherwise you will hear splashing. The valve is installed to regulate the water flow so that the siphon is created and can not flow fast enough to break the siphon by emptying the water chamber. This is all that is required, but there are two main problems:
regulation (so it is kept silent)
possible blockage (pesky snails
or is that algae).
So the idea of an emergency drain came in. The emergency drain is set higher than the regular drain, and if the main drain becomes blocked takes a partial or full amount of the water. It should drain above the water so that splashing is heard if it is active. The Herbie method then balances the water height between the two drains.
Balancing can be very hard especially if the height difference was very small. Someone realized that if the water level is adjusted so that a small amount of water went in the emergency drain it was much more stable. But if the emergence drain is being used is it really an emergency drain? So a third drain was added (BeanAnimal).
From now on they will be referred to as the siphon, open drain and emergency drain. It is a personal call how much redundancy you want some people are talking four drains.
WARNING
This may not work with HOB they are siphon driven from the main tank. If a drain fails the water level start to rise to the next drain. Now there is less flow from the tank since the tank/HOB water differential is less. So the tank may fill up faster than the siphon can fill the HOB.
Siphon Drain
This can be a straight pipe. The only requirement is that it can not suck air. BeanAnimal shows an elbow, because of is relatively low water height. There are many ways to prevent a siphon this is just one. This should drain into the sump just below water level; too far and it will be hard to start the siphon. If there is a choice this should be the smallest of the existing bulkheads.
Open Drain
This is not used in the Herbie design. This is often made into a Durso type standpipe to keep it silent. It should have a minimal amount of water flow,
Emergency Drain
This should be higher than the other standpipe(s), but low enough that the water can create a full siphon if needed. Only have two bulkheads? Instead of using one for the Siphon drain create the siphon drain with piece of tubing going over the back. It will have to be restarted if there is a power failure, but you are no worse off then if you did not have it (is this an original thought
).
Siphon
As the water fills the overflow it will drain down the siphon drain. If the pipe can not handle the water flow with the valve all the way open you have a problem. Now back the valve off until the water level is just going down the open drain (BeanAnimal) or between the two drains (Herbie). Some people have reported problems creating the original siphon. BeanAnimal suggests a small whole just below sump water level. It can also help to have the siphon intake lower than the open drain so that it gets more pressure to start the siphon.
Stand Pipe
This is for those with an over flow box in tank. Do you need one? NO. The reason for a stand pipe is to keep to much water returning to the sump in the event of a power failure.
Screens
Required? NO. They are highly recommended to keep items from getting into the drains (even the emergency drain). This is a comfort level call.
Emergency Drain
Required? No. It will work without. You may just be asking for trouble. Once again this is a comfort call.
Two Drains "“ Over Flows
This is pure theory, but may explain why some people are having problems.
I do not think that two drains can have different flow rates unless one is to the top of the overflow. Assuming a level tank half the water will go into each overflow. So if they do not both drain half the water then one should eventually fill up. I said it was theory Also two drains are hard to adjust (so I have read), so I think the best advice is to tie them together before the gate valve.
Teeing Drain to 2 Locations
This is very hard to adjust. People have done it by gating one of the tees. Also both drains should be in the water for silence so both levels will need to be the same. Despite this I have read of people having one their fuges lower than the sump and/or the other way around. I guess that the water picked the easiest path and then created a venture that sucks the water out of the other container. Unless you want to fine tuning I do not think this is recommended.
Also if you tie them together too soon you break the siphon and will mix air in (pronounced noise).
I think the best might be to drain all pipes into a closed box and have the overflow of that feed the two (or more) section of the sump. Note that water will be pushed up the open and emergency drain to equalize the pressure need to push the water out of the box. (Another new thought??)
Guide lines
- Use the smaller pipe for the main drain
- Keep the drain return simple and as strait as possible
- Drain into a bucket (fixed water level) to keep the output level constant.
- Emergency drain is above the water; you get splash warning that something is wrong.
- Think about on over the top siphon
- Two drains should be tied before the gating valve
- Teeing the drain to a sump a fuge is not recommended
- Water level above pump should be constant
But that is what can make this hobby fun - experimenting.
